Showing papers on "Ultrasonic flow meter published in 1990"

Coriolis mass flow rate meter having a substantially increased noise immunity

Abstract: Apparatus and accompanying methods for use therein for a Coriolis mass flow rate meter which is substantially immune to noise, and more particularly, to such a meter that is substantially unaffected by noise that occurs at substantially any frequency different from a fundamental frequency at which the flow tube(s) in the meter vibrate Specifically, the meter relies on measuring mass flow rate by determining the phase difference that occurs between real and imaginary components of the discrete fourier transform (DFT) of both the left and right velocity sensor waveforms evaluated at the fundamental frequency at which the flow tubes vibrate The fundamental frequency is located, during an initialization operation, by providing a power spectrum, determined through use of the DFT, of one of the sensor signals and then selecting that frequency at which the magnitude of the power spectrum reaches a maximum value In addition, the frequency at which both velocity sensor signals is sampled is readjusted in response to any change in the phase of one of the velocity sensor signals, as transformed using the DFT, in order to assure that the sampling frequency always remains substantially equal to a pre-defined integer multiple of the fundamental frequency Furthermore, the meter, through use of the numerical value of any such phase change, also provides a density indication which is also substantially immune to such noise

Volumetric blood flow via time-domain correlation: experimental verification

Abstract: A novel ultrasonic volumetric flow measurement method using time-domain correlation of consecutive pairs of echoes has been developed. An ultrasonic data acquisition system determined the time shift between a pair of range gated echoes by searching for the time shift with the maximum correlation between the RF sampled waveforms. Experiments with a 5-MHz transducer indicate that the standard deviation of the estimate of steady fluid velocity through 6-mm-diameter tubes is less than 10% of the mean. Experimentally, Sephadex (G-50; 20-80 mu m dia.) particles in water and fresh porcine blood have been used as ultrasound scattering fluids. Two-dimensional (2-D) flow velocity can be estimated by slowly sweeping the ultrasonic beam across the blood vessel phantom. Volumetric flow through the vessel is estimated by integrating the 2-D flow velocity field and then is compared to hydrodynamic flow measurements to assess the overall experimental accuracy of the time-domain method. Flow rates from 50-500 ml/min have been estimated with an accuracy better than 10% under the idealized characteristics used in this study, which include straight circular thin-walled tubes, laminar axially-symmetric steady flow, and no intervening tissues. >

Coriolis densimeter having substantially increased noise immunity

Abstract: Apparatus and accompanying methods for use therein for a Coriolis mass flow rate meter which is substantially immune to noise, and more particularly, to such a meter that is substantially unaffected by noise that occurs at substantially any frequency different from a fundamental frequency at which the flow tube(s) in the meter vibrate. Specifically, the meter relies on measuring mass flow rate by determining the phase difference that occurs between real and imaginary components of the discrete fourier transform (DFT) of both the left and right velocity sensor waveforms evaluated at the fundamental frequency at which the flow tubes vibrate. The fundamental frequency is located, during an initialization operation, by providing a power spectrum, determined through use of the DFT of one of the sensor signals and then selecting that frequency at which the magnitude of the power spectrum reaches a maximum value. In addition, the frequency at which both velocity sensor signals is sampled is readjusted in response to any change in the phase of one of the velocity sensor signals, as transformed using the DFT, in order to assure that the sampling frequency always remains substantially equal to a pre-defined integer multiple of the fundamental frequency. Furthermore, the meter, through use of the numerical value of any such phase change, also provides a density indication which is also substantially immune to such noise.

Ultrasonic flowmeter unit to be inserted in a measuring tube

Abstract: An ultrasonic (US) flow meter unit (E) for installation in a measuring tube (M) especially for air mass measurements in a motor vehicle engine, having two US transducers (2, 3) which operate alternately as transmitting transducer or receiving transducer, the two US transducers (2, 3) being arranged opposite one another in the beam direction in order to form a sound path, passing through the measuring tube (M) and inclined against the flow direction, for US waves between the respective US transmitting transducer and the respective US receiving transducer. Provision is made of a carrying and mounting plate (1) for carrying one of the US transducers (2), as well as for the sealing mounting of the unit (E) over an accommodating opening (5) for the unit (E) in the measuring tube (M). One US transducer (2) and the other US transducer (3) are arranged, by means of a retaining construction (4) that is flexurally rigid and pervious to the flow, inclined and axially aligned with one another at a predetermined angle against the direction of flow in such a way that a sound path required between the two US transducers (2, 3) for the purpose of flow measurement is formed inside the measuring tube (M). The carrying and mounting plate (1) carries an operating and measurement electronics unit (6) on its side averted from the measuring tube (M). The electrical leads required for the US transducer (3) remote from the accommodating opening are integrated in the retaining construction (4).

Measurement of fluid properties of two-phase fluids using an ultrasonic meter

Abstract: A method is disclosed for determining the composition of a two-phase fluid, such as saturated steam In that method, the transit times of sound are measured within the two-phase fluid, the speed of sound of the two-phase fluid is calculated from the measured transit times, and the composition of the two-phase fluid is calculated from the calculated speed of sound From the calculated linear velocity and the calculated composition, one can calculate at least one fluid property of the two-phase fluid, such as mass flow rate or energy flow rate All of these calculations can be performed by a microprocessor

Fluid flow meters

Abstract: A fluid flow meter of the fluidic oscillator type and suitable for electrically conducting liquids, for example for metering domestic water supplies, comprises a feed back oscillator with magnets (8, 9, 12, 13) creating a magnetic field across at least one of the flow paths and a pair of electrodes (10, 11, 14, 15, 16) detecting the resultant potential difference across the flow path. The frequency of the detected signal gives a measure of the flow rate and a counter of the cycles will give the total flow over a period.

Mass air flow meter

Abstract: Improvements in a mass air flow meter for internal combustion engines are disclosed which comprise structure for improving the flow dynamics of the air flow through the sampling path including expansion of the dynamic range and increase of the signal to noise ratio resulting in improved engine performance, fuel efficiency, and emission control. Such structure includes a sample tube being tapered in decreasing area in the direction of air flow therethrough and a pneumatic equivalent of a low pass R C filter which decouples the high turbulence in the main flow through the venturi, averages same and provides a scaled down profiled flow through the sample tube for measurement by a transducer in the sample tube, the measurements having an accuracy of ±2% of reading.

Gas/liquid ultrasonic flowmeter

Abstract: Improvement to a gas/liquid ultrasonic flowmeter in which focusing profiling (501, 502, 503) is provided in the measurement tube thereof for at least one of the plurality of reflection points of the ultrasonic path (21) of the useful signal, in such a manner that the beam of this beam path (21) is concentrated onto the surface of the reception transducer (FIG. 3 ). If required, the focusing reflection is provided for the path of the ultrasonic radiation (22) of the substantial interference signal component.

Verbesserung fuer einen ultraschall-gas-/fluessigkeits-durchflussmesser

Abstract: In order to improve a gas/liquid ultrasonic flowmeter, at least one among a plurality of reflecting sites in the ultrasonic path (21) of the working signal in the measurement tube is designed (501, 502, 503) so as to focalize the beam of rays in this radiation path (21) on the surface of the receiving transducer (figure 3). If necessary, the focalizing reflection in the path of the ultrasonic radiation (22) concerns essentially the disturbing fraction of the signal.

Ultrasonic diagnostic apparatus detecting Doppler shift

Abstract: By transmitting ultrasonic waves along a section of an object under examination, brightness modulating reflected ultrasonic waves from respective points in the section to obtain a B-mode tomography image, and displaying Doppler shifted frequencies of the reflected ultrasonic waves from the respective points in the tomography image in colors, a Doppler flow mapping image indicating blood flow two-dimensionally can be obtained. Also, by transmitting ultrasonic waves many times only in the direction of a desired observation point and analyzing the spectrum of Doppler shifted frequencies of reflected ultrasonic waves from the observation point, a blood flow pattern waveform indicating time-varying blood flow velocity can be obtained. In an ultrasonic diagnostic apparatus which transmits ultrasonic waves repeatedly to a subject under examination at regular intervals and detecting Doppler shifts of reflected ultrasonic waves to obtain the Doppler flow mapping image and the blood flow pattern waveform, by transmitting ultrasonic waves alternately in the direction needed to prepare the Doppler flow mapping image and in the direction needed to prepare the blood flow pattern waveform at each time of transmission of ultrasonic waves, the Doppler flow mapping image and the blood flow pattern waveform can be displayed simultaneously while improving detectable low velocity in the Doppler flow mapping image without degrading aliasing velocity in the blood flow pattern waveform.

Mass flow meter working on the coriolis principle

Abstract: The flow meter works on the Coriolis principle and has a measuring tube and at least two energy converters. At least one of the energy converters is an oscillation exciter for oscillating the tube to generate a wave traveling along the tube and an oscillation detector. An evaluating circuit uses the speed of travel of waves in the direction of flow of fluid through the tube and in the direction opposite the direction of flow to determine the mass flow of fluid through the tube.

Fluid flowmeter for measuring ultrasound transit times

Abstract: In this flowmeter, a measuring tube (9) enclosed by a jacket tube (1) has ultrasonic reflectors and openings for the entry and exit of an ultrasonic beam. The ultrasonic beam is generated by ultrasonic transducers (18, 19) radiating and receiving in the direction of their axis of symmetry, which are arranged in a fluid-tight metal-encapsulated manner in the jacket tube (1). The ultrasonic rays entering and leaving the measuring tube (9) perpendicularly to the direction of flow of the medium are directed by first reflectors (26, 27) at an angle of 22.5 DEG of their reflection surfaces, with respect to the direction of flow of the medium, towards the further reflectors (28, 29, 30), the reflection surfaces of which are arranged parallel to the flow direction of the medium.

Doppler blood flow system and method using low frequency noise signal processing

Abstract: A Doppler blood flow system and method in which an ultrasonic wave is reflected off of red blood cells in blood flowing in tubing. The reflected ultrasonic wave is digitally processed in the frequency domain. The flow rate of the blood is directly related to the average frequency of the Doppler signal. The typical Doppler signal is not a single frequency representing a single flow rate but is really an entire range of frequencies in which certain frequencies predominate which are indicated by increased amplitude of the signal when plotted in the frequency domain. The typical Doppler signal may actually have two "humps", one at a higher frequency which represents the actual information bearing content of the signal related to flow rate and one at a lower frequency which is caused by vibrations in the blood tubing system itself and could be caused by motor noise from the blood pump. Since the flow rate is related to average frequency of the information bearing portion of the typical Doppler signal, the low frequency "hump" must be taken out of the Doppler signal in order to obtain an accurate flow rate.

Ultrasonic flow meter

Abstract: Ultrasonic flow meter with a W-shaped ultrasound path inside the measurement tube (1) and with a stepped elevation/depression of the internal wall of the tube at the site of reflection of the parasitic V-shaped path.

Method and flowmeter for unsteady fluid flow study

Abstract: An electromagnetic flowmeter and a method for measurement of the rate of flow of a fluid under unsteady conditions are described. It uses fluid steady-state flowmeter technology and a new algorithm to measure transient rate of flow of a fluid such as water. The algorithm teaches (a) measuring the e.m.f. generated due to the rate of flow of the fluid under test moving through a tube placed in an area with uniform magnetic flux, and (b) comparing it to a simultaneously generated reference signal which is measure of the magnetic flux density generated when an electromagnetic flowmeter is energized due to the fluid flow rate at the instant of taking the flow rate data of the fluid.

Ultrasonic ground speedometer utilizing doppler effect

Abstract: An ultrasonic ground speedometer utilizing Doppler effect comprises an ultrasonic transmitter (1,2,3) for outputting an ultrasonic wave (4) having a particular wavelength (ϑ) at a predetermined angle against a road surface (5), an ultrasonic receiver (6,7,8) for receiving a reflected ultrasonic wave caused by reflection of the output ultrasonic wave from the road surface, and a signal processor (10,11,12) for deriving ground speed from Doppler shift between the output ultrasonic wave and the reflected ultrasonic wave. The particular wavelength is set to a value within a range of 2.6 mm through 3.4 mm to assure the highest possible S/N ratio for the Doppler shift signal obtained from the signal processor.

Doppler blood flow system and method using special zero flow rate analysis

Abstract: A Doppler blood flow system and method in which an ultrasonic wave (16) is reflected off of red blood cells (24) in blood flowing in tubing (20). The reflected ultrasonic wave (26) is digitally processed in the frequency domain. The flow rate of the blood is directly related to the average frequency of the Doppler signal. Because the Doppler blood flow system calculates flow rate solely on the basis of frequency, a special case exists at zero rate of flow where the received signal is not a valid Doppler flow signal, but rather purely noise. The noise at zero flow rate is random and will not have an average frequency which is unique to zero flow. The Doppler blood flow system and method must invoke a special case determination of when a zero flow condition in order to accurately provide a blood flow rate. The system utilizes a method of determining the rate of flow of a fluid containing particles flowing through a tube. An ultrasonic signal is transmitted through the tube at an oblique angle thereto. The ultrasonic signal which has been reflected off of the particles contained in the fluid is received as a received ultrasonic signal. The rate of flow of the fluid is calculated from the received ultrasonic signal using Doppler techniques. Whether the special case of the value of the rate of flow being equal to zero exists is determined and the value of the rate of flow is set equal to zero for the special case.

Application of a surface-acoustic-wave device for measurement of liquid flow rate

Abstract: The use of a surface-acoustic-wave (SAW) device to measure the flow rate of liquids is described. A delay-line stabilized SAW oscillator heated to a suitable temperature above ambient is cooled by the flowing fluid. This results in a change in the oscillator frequency. The frequency of a 68-MHz oscillator operated at 9 degrees C above ambient is found to vary by more than 40 kHz for variation in water flow rate from 0 to 0.8 ml/min. Attractive features of this device include the ability to measure very low flow rates (less than 0.1 mu l/min) and direct digital output. However, since this is a thermal type of flow sensor, the temperature of the fluid will be slightly elevated during its passage through the flow cell. The device should be useful in applications where low flow rates have to be monitored. >

Improvement to gas/liquid ultrasonic flowmeter

Abstract: In order to improve a gas/liquid ultrasonic flowmeter, at least one among a plurality of reflecting sites in the ultrasonic path (21) of the working signal in the measurement tube is designed (501, 502, 503) so as to focalize the beam of rays in this radiation path (21) on the surface of the receiving transducer (figure 3) If necessary, the focalizing reflection in the path of the ultrasonic radiation (22) concerns essentially the disturbing fraction of the signal

Extended range flow meter

Abstract: This invention concerns an extended range flow meter and method of providing continuous metering of fluid flow utilizing of two or more flow meters by the more accurate flow meter or combination of flow meters at a given flow volume.

Ultrasonic flow meters

Abstract: Widely fluctuating demand has led Enogex (USA) to install ultrasonic flow meters on gas pipelines feeding an Oklahoma electric power generating station.

Model studies of nonsteady flow using magnetic resonance imaging.

Abstract: A bolus-tracking magnetic resonance imaging (MRI) method has been employed to measure velocity profiles for oscillatory flow with and without a steady flow component as well as pulsatile flow in an axisymmetric tube model. A range of flow conditions within normal physiological limits was tested. The imaged velocity profiles were observed to be generally in accord with theoretical predictions. Instantaneous flow rates calculated from the MR images agreed well with those assessed using an ultrasonic flowmeter. Because MRI is noninvasive and poses few risks to subjects, this technique is potentially useful for studying vascular hemodynamics in vivo.

Flow meter for measuring fluid flow with multiple temperature sensors

Abstract: A part of a tube, through which a fluid passes, is cooled by means of an electronic cooling element and a flow rate of the fluid is measured on the basis of a temperature of a surface of the tube cooled. Not only can the flow rate of the liquid flowing through the tube be determined in a noncontacting manner and a very small flow rate of the liquid be determined, but also the tube is cooled so that no bubbles are generated, and thus the measurement of the liquid, which is apt to generate gases, such as low boiling point liquid, is possible. In addition, the measurement is not influenced by the gases dissolved in the liquid and merely the temperature difference resulting from the flow of the fluid, that is, the rise of the temperature of the fluid, is detected to prevent the measurement from being influenced by the installing posture of the flow meter, so that a highly accurate measurement is possible. Consequently, stable and sure controlling flow rate of liquid is possible.

Clinical evaluation of a diameter sensing Doppler cardiac output meter.

Abstract: A concentric beam Doppler ultrasonic flowmeter has been developed. This instrument has capacity for independent assessment of volumetric flow, as it determines flow cross-section area, stroke length, and pulse rate from the Doppler signals alone. The method is practically independent of the angle of interrogation. We used this device and obtained noninvasive estimates of cardiac output in 54 patients undergoing invasive assessment of cardiac output by thermodilution, Fick, or indicator dye methods (x). Correlations against pooled cardiac output reference standards ranged from r = .86 (y = .86x + 1.03) in 26 studies of high confidence to r = .45 (y = .30x + 2.62) in 17 studies under difficult conditions. The overall correlation was r = .68 (y = .63x + 1.49, n = 87). Noninvasive results of experienced and inexperienced operators were similar (r = .87). The instrument returned accurate assessments of heart rate (r = .83), but underestimated stroke length (r = .72) and appeared to be limited in the assessment of aortic diameters less than 28 or greater than 31 mm (r = .23). We conclude that stand-alone Doppler assessment of cardiac output is appealing and feasible, but difficult or impossible in many ICU scenarios. Further evolution of the concentric beam Doppler approach is needed and anticipated.

Diverging signal tandem doppler probe

Abstract: A dual transducer probe for measuring blood flow by Doppler effect measurement in which quantitative flow data can be compiled and flow constriction points as small as 10% and less can be pinpointed with relative ease. The probe is formed with two transducers, oriented at about 45° from a bottom contacting surface of the probe so that transmission signals diverge at an angle of about 90°. A first transducer directs pulsed sound waves into the direction of blood flow and a second transducer directs pulsed sound waves with the direction of blood flow. The transducers act as receivers for the respective pulses. Fluid velocity can be calculated due to the Doppler effect. By analyzing the signal frequency shifts from the two transistors the blood flow at a very minute region between the transducers, can be determined. Constrictions, corresponding to changes in flow can be pinpointed by moving the probe along the blood vessel.

Quantitative color flow imaging to measure the two-dimensional distribution of blood flow velocity and the flow rate.

Abstract: A quantitative Doppler color flow imaging was employed to measure the two-dimensional distribution of blood flow velocity and flow rate in a large vessel. Regional blood flow velocity was determined by converting the color intensity at the respective pixel into corresponding flow velocity and correcting the flow velocity for spatial ultrasound beam incident angle. Instantaneous flow rate was determined precisely from the image of velocity distribution on the cross-section of the flow tract in a steady flow model circuit. In clinical application, the differences in phasic changes in two-dimensional velocity distribution in the ascending aorta, between normal subjects and the patient with aortic regurgitation, were clearly depicted. The quantitative color flow imaging may have great potential to determine noninvasively and real-timely the two-dimensional distribution of flow velocity as well as flow rate in a large vessel.

Measuring tube for ultrasonic flow measurements

Abstract: The outer sheath (1a, 1b) of a measuring tube (1) for ultrasonic flow measurements using the propagation time method is provided, in the region of the ultrasonic beams impinging on the measuring pipe inner wall, with a sawtooth-shaped external profile, whose cross-sectional surface consists of approximately right-angled triangles arranged one after the other, whose base runs in the flow direction and whose small legs are turned towards the nearest ultrasonic converter (3, 4) in the direction of the transmitted beam and whose height is approximately equal to the wavelength of the ultrasonic frequency

Ultrasonic mass flow meter

Abstract: Methods and apparatus (1) for measuring the mass flow rate of solids suspended in a gas stream (2) flowing along a pipe (3). Two ultrasonic transducers (4, 5) are mounted in short side arms (6, 7) extending from the pipe. The transducers are arranged such that signals are transmitted from one to the other through the gas stream at an angle Υ, usually about 45°. The received signals in both transducers are received by apparatus (8) and amplified. The invention allows determination of: the mean times for the ultrasonic pulses to travel from one transducer (4) to another (5) and vice-versa; the mean peak amplitude of received pulses; and, the standard deviation or spread of these parameters. The mean times taken for the ultrasonic signals to travel between the transducers are used to determine the gas flow velocity, and the mean peak amplitudes for calculating the solids loading. From these the mass flow rate is derived. The invention is applicable to determining mass flow rates of pulverised coal contained in an air flow in a large power station.

Volumetric flow rate measurements in oscillating pipe flows with a laser-Doppler sensor

Abstract: The authors deal with a measuring technique for low flow rate measurements. They describe a sensor that uses a laser-Doppler anemometer as the basic measuring technique to yield instantaneous flow rate information. The principle of the measuring device is explained and it is shown that the axial velocity of a pipe flow can be utilised to obtain the volumetric flow rate. If information on the velocity profile shape is readily available, no calibration of the instrument is required. Using this measuring principle in conjunction with the high measuring precision of laser-Doppler anemometry allows a highly precise instrument to be designed and built for flow rate measurements. The authors show that this instrument has also the capability to carry out instantaneous flow rate measurements. Time-averaged and instantaneous flow rates can both be measured, the latter up to a limiting frequency given by the pipe diameter and the viscosity of the fluid.

Widebeam ultrasonic flowmeter

Abstract: A novel method of a clamp-on ultrasonic flowmeter is proposed. With this method, a widebeam is examined theoretically by the application of spatial frequency analysis. It is demonstrated that plate modes generated in a pipe wall exert bad effects on flowrate measurement. This method can reduce such effects. This method makes it possible to automatically compensate for the deviation of the transit path caused by the temperature change, and to measure the flowrate even if the sound velocity is unknown. >